1
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Sakai M, Ohira M, Gomi T. Spatiotemporal patterns in differences between the 137Cs concentrations of forest and stream litters: effect of leaching. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:1385-1390. [PMID: 37522302 DOI: 10.1039/d3em00236e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Forest-stream ecotones possess prominent detritus-based food webs, and 137Cs-contaminated litter can influence the contamination levels of animals inhabiting such ecosystems. The effects of leaching on contaminated litter induce greater absolute differences between the 137Cs concentrations of forest and stream litter in more contaminated sites. Because 137Cs concentrations in litter can be attenuated temporally, spatiotemporal patterns in the differences in 137Cs concentrations between forest and stream litter may vary depending on both the amount of 137Cs deposition and the passage of time. To test this hypothesis, we sampled coniferous needle and broad-leaved deciduous litter in forests and streams at seven forested headwater sites affected by the Fukushima nuclear accident 3.24 and 11.24 years after the accident. We found that 137Cs concentrations in the two litter types were one order of magnitude lower 11.24 years after the accident than 3.24 years afterwards. The absolute difference in 137Cs activity concentrations of litter between forest and stream ecosystems was higher at more contaminated sites both 3.24 and 11.24 years after the accident. The spatiotemporal changes in litter contamination provide insight into 137Cs dynamics and complex transfer in the detritus-based food webs of forest-stream ecotones.
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Affiliation(s)
- Masaru Sakai
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Fukushima 963-7700, Japan.
| | - Mitsuru Ohira
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Sauwau-cho, Fuchu, Tokyo 183-8509, Japan
- Field Science Center for Northern Biosphere, Hokkaido University, 131 Toikanbetu, Horonobe-cho, Teshio-gun, Hokkaido 098-2943, Japan.
| | - Takashi Gomi
- Institute of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Sauwau-cho, Fuchu, Tokyo 183-8509, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nogoya, Aichi 464-8601, Japan.
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2
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Nishina K, Hayashi S, Hashimoto S, Matsuura T. Estimation of spatio-temporal distribution of 137Cs concentrations in litter layer of forest ecosystems in Fukushima using FoRothCs model. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 328:121605. [PMID: 37059170 DOI: 10.1016/j.envpol.2023.121605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/18/2023] [Accepted: 04/07/2023] [Indexed: 05/09/2023]
Abstract
The nuclear power plant accident in Fukushima had led to pollution of forest ecosystems with 137Cs in 2011. In this study, we simulated the spatiotemporal distribution of 137Cs concentrations of litter layer in the contaminated forest ecosystems in two decades from 2011, which is one of the key environmental components of 137Cs migration in the environment due to the high bioavailability of 137Cs in the litter. Our simulations showed that 137Cs deposition is the most important factor in the degree of contamination of the litter layer but vegetation type (evergreen coniferous/deciduous broadleaf) and mean annual temperature are also important for changes over time. Deciduous broadleaf trees had higher initial concentrations in the litter layer due to the direct initial deposition on the forest floor. However, the concentrations remained higher than those in evergreen conifers after 10 years due to redistribution of 137Cs by vegetation. Moreover, areas with lower average annual temperatures and lower litter decomposition activity retained higher 137Cs concentrations in the litter layer. The results of the spatiotemporal distribution estimation of the radioecological model suggest that, in addition to 137Cs deposition, elevation and vegetation distribution should also be considered in the long-term management of contaminated watersheds, which can be informative in identifying hotspots of 137Cs contamination on a long-term scale.
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Affiliation(s)
- Kazuya Nishina
- Earth System Division, National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, 305-8506, Japan.
| | - Seiji Hayashi
- Fukushima Branch, National Institute for Environmental Studies, 10-2, Fukuasaku, Miharu, 963-7700, Japan
| | - Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1, Matsunosato, Tsukuba, 305-8687, Japan; Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Toshiya Matsuura
- Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka, Tsukuba, 020-0123, Japan
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3
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Sakakibara K, Iwagami S, Tsujimura M, Konuma R, Sato Y, Onda Y. Radiocesium leaching from litter during rainstorms in the Fukushima broadleaf forest. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 796:148929. [PMID: 34328892 DOI: 10.1016/j.scitotenv.2021.148929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
Forests are important sources of dissolved radiocesium (137Cs) discharge downstream. To improve understanding of dissolved 137Cs discharge processes during rainstorms, we investigated the relationship between rainfall-runoff hydrological processes and the discharge of 137Cs leached from litter. Leaching tests were conducted with broadleaf litter collected in the area where saturated overland flow was generated during rainstorms in a broadleaf-tree-dominated forest. According to the leaching test results, the 137Cs leaching rate was higher in the early stage of the test and decreased afterward. There was no significant difference in the overall results between the agitation and non-agitation cases. The 137Cs leaching rate from litter after the 24-h test was up to 33.7%. A large proportion of the original 137Cs activity was present even after the tests, as leaching from litter during rainstorms in the headwater area could be an additional source of dissolved 137Cs in the stream water. If mixing of 137Cs originating from groundwater, soil water, and rainfall with the hydrological processes is assumed, differences between the observed and estimated 137Cs in the surface runoff water became larger under high flow conditions. This analysis indicates additional 137Cs loading on surface runoff water during rainstorms, where saturated surface area can expand as the surface runoff rate increases. Contact area between surface runoff and litter accumulated on the forest floor should increase and accelerate 137Cs leaching from the litter. Therefore, 137Cs leaching in the saturated surface area that is temporarily formed during rainstorms can play a principal role in dissolved 137Cs discharge during rainfall-runoff events. Contaminated litter in the temporally saturated region of forested headwaters is an important factor contributing to elevated levels of dissolved 137Cs during rainstorms in the Fukushima area.
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Affiliation(s)
| | - Sho Iwagami
- Department of Disaster Prevention, Meteorology and Hydrology, Forestry and Forest Products Research Institute, Ibaraki, Japan
| | - Maki Tsujimura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan.
| | - Ryohei Konuma
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yutaro Sato
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yuichi Onda
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan; Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Ibaraki, Japan
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4
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Sakai M, Tsuji H, Ishii Y, Ozaki H, Takechi S, Jo J, Tamaoki M, Hayashi S, Gomi T. Untangling radiocesium dynamics of forest-stream ecosystems: A review of Fukushima studies in the decade after the accident. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 288:117744. [PMID: 34243085 DOI: 10.1016/j.envpol.2021.117744] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
Forest-stream ecosystems are widespread and biodiverse terrestrial landscapes with physical and social connections to downstream human activities. After radiocesium is introduced into these ecosystems, various material flows cause its accumulation or dispersal. We review studies conducted in the decade after the Fukushima nuclear accident to clarify the mechanisms of radiocesium transfer within ecosystems and to downstream areas through biological, hydrological, and geomorphological processes. After its introduction, radiocesium is heavily deposited in the organic soil layer, leading to persistent circulation due to biological activities in soils. Some radiocesium in soils, litter, and organisms is transported to stream ecosystems, forming contamination spots in depositional habitats. While reservoir dams function as effective traps, radiocesium leaching from sediments is a continual phenomenon causing re-contamination downstream. Integration of data regarding radiocesium dynamics and contamination sites, as proposed here, is essential for contamination management in societies depending on nuclear power to address the climate crisis.
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Affiliation(s)
- Masaru Sakai
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan.
| | - Hideki Tsuji
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Yumiko Ishii
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Hirokazu Ozaki
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Seiichi Takechi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Jaeick Jo
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Masanori Tamaoki
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Seiji Hayashi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, Japan, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, 963-7700, Japan
| | - Takashi Gomi
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
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5
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Okada K, Sakai M, Gomi T, Iwamoto A, Negishi JN, Nunokawa M. Seasonal variations of
137
Cs
concentration in freshwater charr through uptake and metabolism in 1–2 years after the Fukushima accident. Ecol Res 2021. [DOI: 10.1111/1440-1703.12266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Kengo Okada
- Graduate School of Agriculture Tokyo University of Agriculture and Technology Tokyo Japan
| | - Masaru Sakai
- Fukushima Regional Collaborative Research Center National Institute for Environmental Studies Fukushima Japan
| | - Takashi Gomi
- Graduate School of Agriculture Tokyo University of Agriculture and Technology Tokyo Japan
| | - Aimu Iwamoto
- Graduate School of Agriculture Tokyo University of Agriculture and Technology Tokyo Japan
| | - Junjiro N. Negishi
- Faculty of Environmental Earth Science Hokkaido University Hokkaido Japan
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6
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Sakuma K, Yoshimura K, Nakanishi T. Leaching characteristics of 137Cs for forest floor affected by the Fukushima nuclear accident: A litterbag experiment. CHEMOSPHERE 2021; 264:128480. [PMID: 33032218 DOI: 10.1016/j.chemosphere.2020.128480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 09/09/2020] [Accepted: 09/27/2020] [Indexed: 06/11/2023]
Abstract
In forest ecosystems, forest litter is considered an active medium for radiocesium (137Cs). To understand discharge mechanisms of highly bioavailable dissolved 137Cs from forests to river systems, we investigated the characteristics of 137Cs leaching from forest litter as observed from litterbag experiments. Leaching experiments with conifer needle and deciduous broadleaf litters were then conducted. After soaking conifer needles and broadleaf litters for 20 min, 140 min, and 1 day, the mean values of the 137Cs leaching ratios were 0.13-2.0% and 0.81-6.6%, respectively, indicating that 137Cs leaching ratios are different between forest litter types. To elucidate the factors affecting 137Cs leaching from forest litter, a multi-regression analysis of 137Cs leaching ratios was conducted against antecedent mean precipitation and temperature before sampling the litterbag and accumulated temperature during the litterbag experiments. The 137Cs leaching ratios showed a negative correlation to the antecedent mean precipitation for both litters and the accumulated temperature for broadleaf litters, whereas it exhibited a positive correlation with the antecedent mean temperature for both litters and the accumulated temperature for conifer needle litters. It was proposed that the fraction of 137Cs in labile sites in forest litter increased/decreased due to litter decomposition by antecedent/accumulated temperature, and that this fraction can be washed off by the antecedent precipitation. The different effects of accumulated temperature on 137Cs leaching from conifer needles and broadleaf litters could be due to their different decomposition rates. Our results contribute further the understanding of the mechanisms associated with dissolved 137Cs discharge from forested catchments.
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Affiliation(s)
- Kazuyuki Sakuma
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Fukushima, 963-7700, Japan.
| | - Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Fukushima, 963-7700, Japan
| | - Takahiro Nakanishi
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Fukushima, 963-7700, Japan
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7
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Iwagami S, Onda Y, Sakashita W, Tsujimura M, Satou Y, Konuma R, Nishino M, Abe Y. Six-year monitoring study of 137Cs discharge from headwater catchments after the Fukushima Dai-ichi Nuclear Power Plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 210:106001. [PMID: 31272804 DOI: 10.1016/j.jenvrad.2019.106001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 07/25/2018] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
Since headwater catchments are the source areas of 137Cs for downstream river systems, 137Cs discharge from headwater areas needs to be evaluated. Dissolved form (Dissolved), coarse organic matter (Org), and suspended sediments (SS) were sampled and 137Cs concentrations were measured from June 2011 to November 2016 in four headwater catchments in Yamakiya District, located 35 km northwest of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP). The data up to September 2013 (2.5 y after the accident) have been already published (Iwagami et al., 2017a, b). The data up to November 2016 (5.7 y after the accident) are newly reported in the present paper together with data at a new sampling site. The whole data from June 2011 to November 2016 is discussed. The normalized 137Cs concentrations (137Cs concentrations normalized by the average deposition density of each catchment) in Dissolved, Org, and SS were in the order of 10-6 m2/L, 10-2 m2/kg, and 10-1 m2/kg, respectively, before 2013 and declined to around 10-8 m2/L, 10-4 m2/kg, and 10-2 m2/kg, respectively, in 2016. As a result of the decontamination program, the discharge of SS increased, whereas 137Cs concentrations in SS declined significantly and the total flux of 137Cs decreased. Although the clear effect of land use on decline trend in normalized 137Cs concentrations in Dissolved was not found, more data are necessary for elucidating the relation between them.
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Affiliation(s)
- Sho Iwagami
- Forestry and Forest Products Research Institute, Forest Research and Management Organization, 305-8687, Japan.
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 305-8577, Japan
| | - Wataru Sakashita
- Forestry and Forest Products Research Institute, Forest Research and Management Organization, 305-8687, Japan
| | - Maki Tsujimura
- Faculty of Life and Environmental Sciences, University of Tsukuba, 305-8572, Japan
| | - Yutaro Satou
- Faculty of Life and Environmental Sciences, University of Tsukuba, 305-8572, Japan
| | - Ryohei Konuma
- Faculty of Life and Environmental Sciences, University of Tsukuba, 305-8572, Japan
| | - Masataka Nishino
- Faculty of Life and Environmental Sciences, University of Tsukuba, 305-8572, Japan
| | - Yutaka Abe
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 305-8577, Japan
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8
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Sakuma K, Tsuji H, Hayashi S, Funaki H, Malins A, Yoshimura K, Kurikami H, Kitamura A, Iijima K, Hosomi M. Applicability of K d for modelling dissolved 137Cs concentrations in Fukushima river water: Case study of the upstream Ota River. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 210:105815. [PMID: 30340874 DOI: 10.1016/j.jenvrad.2018.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/25/2017] [Accepted: 01/04/2018] [Indexed: 06/08/2023]
Abstract
A study is presented on the applicability of the distribution coefficient (Kd) absorption/desorption model to simulate dissolved 137Cs concentrations in Fukushima river water. The upstream Ota River basin was simulated using GEneral-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) for the period 1 January 2014 to 31 December 2015. Good agreement was obtained between the simulations and observations on water and suspended sediment fluxes, and on particulate bound 137Cs concentrations under both base and high flow conditions. By contrast the measured concentrations of dissolved 137Cs in the river water were much harder to reproduce with the simulations. By tuning the Kd values for large particles, it was possible to reproduce the mean dissolved 137Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved 137Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters. These discrepancies may be explained by microbial action and leaching from organic matter in forest litter providing an additional input of dissolved 137Cs to rivers, particularly over summer, and limitations of the Kd absorption/desorption model. It is recommended that future studies investigate these issues in order to improve simulations of dissolved 137Cs concentrations in Fukushima rivers.
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Affiliation(s)
- Kazuyuki Sakuma
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan.
| | - Hideki Tsuji
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hironori Funaki
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Alex Malins
- Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hiroshi Kurikami
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Akihiro Kitamura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuki Iijima
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Masaaki Hosomi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
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9
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Kurikami H, Sakuma K, Malins A, Sasaki Y, Niizato T. Numerical study of transport pathways of 137Cs from forests to freshwater fish living in mountain streams in Fukushima, Japan. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:106005. [PMID: 31279227 DOI: 10.1016/j.jenvrad.2019.106005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/21/2019] [Accepted: 06/28/2019] [Indexed: 06/09/2023]
Abstract
The accident at the Fukushima Dai-ichi Nuclear Power Plant in 2011 released a large quantity of radiocesium into the surrounding environment. Radiocesium concentrations in some freshwater fish caught in rivers in Fukushima Prefecture in October 2018 were still higher than the Japanese limit of 100 Bq kg-1 for general foodstuffs. To assess the uptake of 137Cs by freshwater fish living in mountain streams in Fukushima Prefecture, we developed a compartment model for the migration of 137Cs on the catchment scale from forests to river water. We modelled a generic forest catchment with Fukushima-like parameters to ascertain the importance of three export pathways of 137Cs from forests to river water for the uptake of 137Cs by freshwater fish. The pathways were direct litter fall into rivers, lateral inflow from the forest litter layer, and lateral transfer from the underlying forest soil. Simulation cases modelling only a single export pathway did not reproduce the actual trend of 137Cs concentrations in river water and freshwater fish in Fukushima Prefecture. Simulations allowing a combined effect of the three pathways reproduced the trends well. In the latter simulations, the decreasing trend of 137Cs in river water and freshwater fish was due to a combination of the decreasing trend in the forest leaves/needles and litter compartments, and the increasing trend in soil. The modelled 137Cs concentrations within the forest compartments were predicted to reach an equilibrium state at around ten years after the fallout due to the equilibration of 137Cs cycling in forests. The model suggests that long term 137Cs concentrations in freshwater fish in mountain streams will be controlled by the transfer of 137Cs to river water from forest organic soils.
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Affiliation(s)
- Hiroshi Kurikami
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Kazuyuki Sakuma
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Alex Malins
- Japan Atomic Energy Agency (JAEA), Center for Computational Science & e-Systems, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan.
| | - Yoshito Sasaki
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Tadafumi Niizato
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
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10
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Sakuma K, Tsuji H, Hayashi S, Funaki H, Malins A, Yoshimura K, Kurikami H, Kitamura A, Iijima K, Hosomi M. Applicability of K d for modelling dissolved 137Cs concentrations in Fukushima river water: Case study of the upstream Ota River. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 184-185:53-62. [PMID: 29353199 DOI: 10.1016/j.jenvrad.2018.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/25/2017] [Accepted: 01/04/2018] [Indexed: 06/07/2023]
Abstract
A study is presented on the applicability of the distribution coefficient (Kd) absorption/desorption model to simulate dissolved 137Cs concentrations in Fukushima river water. The upstream Ota River basin was simulated using GEneral-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) for the period 1 January 2014 to 31 December 2015. Good agreement was obtained between the simulations and observations on water and suspended sediment fluxes, and on particulate bound 137Cs concentrations under both base and high flow conditions. By contrast the measured concentrations of dissolved 137Cs in the river water were much harder to reproduce with the simulations. By tuning the Kd values for large particles, it was possible to reproduce the mean dissolved 137Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved 137Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters. These discrepancies may be explained by microbial action and leaching from organic matter in forest litter providing an additional input of dissolved 137Cs to rivers, particularly over summer, and limitations of the Kd absorption/desorption model. It is recommended that future studies investigate these issues in order to improve simulations of dissolved 137Cs concentrations in Fukushima rivers.
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Affiliation(s)
- Kazuyuki Sakuma
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan.
| | - Hideki Tsuji
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hironori Funaki
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Alex Malins
- Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hiroshi Kurikami
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Akihiro Kitamura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuki Iijima
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Masaaki Hosomi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
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11
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Gomi T, Sakai M, Haque ME, Hosoda K, Toda H. Evaluating 137Cs detachment from coniferous needle litter in a headwater stream: a litter bag field experiment. LANDSCAPE AND ECOLOGICAL ENGINEERING 2018. [DOI: 10.1007/s11355-017-0337-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Negishi JN, Sakai M, Okada K, Iwamoto A, Gomi T, Miura K, Nunokawa M, Ohhira M. Cesium-137 contamination of river food webs in a gradient of initial fallout deposition in Fukushima, Japan. LANDSCAPE AND ECOLOGICAL ENGINEERING 2017. [DOI: 10.1007/s11355-017-0328-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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